1. Field of the Invention
This invention relates to cameras and more particularly, to prevention of the exposed film from being fogged when it is being rewound.
2. Description of the Prior Art
Recently, the trend of increasing the maximum speed of the shutter of the single lens reflex camera has advanced to 1/4000 sec. and strobe-synchro speed of 1/250 sec. And an even faster shutter, too, comes out. In these shutters, it is required to reduce the mass of the blades. So the shutter blades are thinned to an extreme.
By the way, for the film transportation in the camera, particularly when in the rewind mode, because the film is continuously run in frictional contact with the film gate, static electricity is generated. In the case of motorized rewinding, the running film induces swirling of wind between the shutter and the film gate. Here it will be understood that as it has been customary to employ only the front blade group of the shutter for covering the exposure aperture of the film gate in the shutter-cocked position, if the rewinding is performed under such a condition, the above-mentioned static electricity or air pressure will cause the front blade group to deform with the result that when the front blade group is constructed in the form of a set of extremely thinned plates or blades, it is split in two between the successive blades, permitting light to leak into the exposure aperture. The conventional cameras has, therefore, a problem of fogging the exposed film by such leaked light when the film is being rewound. Such a problem has become very serious when the camera gets the capabilities of speeding up the shutter and motorizing the film rewinding, since the fogging will often take place over the entire area of the film.